When I Ctrl+U it opens View Source, but I need to Underline things.

I was writing in blog post and needed to Underline something and it opened View Source. I opened several other pages and it happened on all of them. Not sure if Firefox didn't recognize wordpress's text editor as a text editor, if there is a different Underline shortcut or if they are just doubled up and View Source takes precedent.

I was writing in blog post and needed to Underline something and it opened View Source. I opened several other pages and it happened on all of them. Not sure if Firefox didn't recognize wordpress's text editor as a text editor, if there is a different Underline shortcut or if they are just doubled up and View Source takes precedent.

The View Source feature doesn't provide for editing the source which is being viewed. Not intended for HTML editing and / or saving of edits.
You can used an external source editor application and use an extension such as this to have Firefox use the external editor.
https://addons.mozilla.org/en-US/firefox/addon/withexeditor/